/**
 *
 * Copyright 2013-2014 Georg Lukas, 2015-2020 Florian Schmaus
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jivesoftware.smackx.receipts;

import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.logging.Logger;

import org.jivesoftware.smack.ConnectionCreationListener;
import org.jivesoftware.smack.Manager;
import org.jivesoftware.smack.SmackException;
import org.jivesoftware.smack.SmackException.NotConnectedException;
import org.jivesoftware.smack.StanzaListener;
import org.jivesoftware.smack.XMPPConnection;
import org.jivesoftware.smack.XMPPConnectionRegistry;
import org.jivesoftware.smack.XMPPException;
import org.jivesoftware.smack.filter.AndFilter;
import org.jivesoftware.smack.filter.MessageTypeFilter;
import org.jivesoftware.smack.filter.MessageWithBodiesFilter;
import org.jivesoftware.smack.filter.NotFilter;
import org.jivesoftware.smack.filter.StanzaExtensionFilter;
import org.jivesoftware.smack.filter.StanzaFilter;
import org.jivesoftware.smack.filter.StanzaTypeFilter;
import org.jivesoftware.smack.packet.Message;
import org.jivesoftware.smack.packet.Stanza;
import org.jivesoftware.smack.packet.StanzaBuilder;
import org.jivesoftware.smack.roster.Roster;
import org.jivesoftware.smack.util.StringUtils;

import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;

import org.jxmpp.jid.Jid;

/**
 * Manager for XEP-0184: Message Delivery Receipts. This class implements
 * the manager for {@link DeliveryReceipt} support, enabling and disabling of
 * automatic DeliveryReceipt transmission.
 *
 * <p>
 * You can send delivery receipt requests and listen for incoming delivery receipts as shown in this example:
 * </p>
 * <pre>
 * deliveryReceiptManager.addReceiptReceivedListener(new ReceiptReceivedListener() {
 *   void onReceiptReceived(String fromJid, String toJid, String receiptId, Stanza receipt) {
 *     // If the receiving entity does not support delivery receipts,
 *     // then the receipt received listener may not get invoked.
 *   }
 * });
 * Message message = …
 * DeliveryReceiptRequest.addTo(message);
 * connection.sendStanza(message);
 * </pre>
 *
 * DeliveryReceiptManager can be configured to automatically add delivery receipt requests to every
 * message with {@link #autoAddDeliveryReceiptRequests()}.
 *
 * @author Georg Lukas
 * @see <a href="http://xmpp.org/extensions/xep-0184.html">XEP-0184: Message Delivery Receipts</a>
 */
public final class DeliveryReceiptManager extends Manager {

    /**
     * Filters all non-error messages with receipt requests.
     * See <a href="https://xmpp.org/extensions/xep-0184.html#when">XEP-0184 § 5.</a> "A sender could request receipts
     * on any non-error content message (chat, groupchat, headline, or normal)…"
     */
    private static final StanzaFilter NON_ERROR_GROUPCHAT_MESSAGES_WITH_DELIVERY_RECEIPT_REQUEST = new AndFilter(
            StanzaTypeFilter.MESSAGE,
            new StanzaExtensionFilter(new DeliveryReceiptRequest()),
            new NotFilter(MessageTypeFilter.ERROR));

    private static final StanzaFilter MESSAGES_WITH_DELIVERY_RECEIPT = new AndFilter(StanzaTypeFilter.MESSAGE,
                    new StanzaExtensionFilter(DeliveryReceipt.ELEMENT, DeliveryReceipt.NAMESPACE));

    private static final Logger LOGGER = Logger.getLogger(DeliveryReceiptManager.class.getName());

    private static final Map<XMPPConnection, DeliveryReceiptManager> instances = new WeakHashMap<>();

    static {
        XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
            @Override
            public void connectionCreated(XMPPConnection connection) {
                getInstanceFor(connection);
            }
        });
    }

    /**
     * Specifies when incoming message delivery receipt requests should be automatically
     * acknowledged with an receipt.
     */
    public enum AutoReceiptMode {

        /**
         * Never send deliver receipts.
         */
        disabled,

        /**
         * Only send delivery receipts if the requester is subscribed to our presence.
         */
        ifIsSubscribed,

        /**
         * Always send delivery receipts. <b>Warning:</b> this may causes presence leaks. See <a
         * href="http://xmpp.org/extensions/xep-0184.html#security">XEP-0184: Message Delivery
         * Receipts § 8. Security Considerations</a>
         */
        always,
    }

    private static AutoReceiptMode defaultAutoReceiptMode = AutoReceiptMode.ifIsSubscribed;

    /**
     * Set the default automatic receipt mode for new connections.
     *
     * @param autoReceiptMode the default automatic receipt mode.
     */
    public static void setDefaultAutoReceiptMode(AutoReceiptMode autoReceiptMode) {
        defaultAutoReceiptMode = autoReceiptMode;
    }

    private AutoReceiptMode autoReceiptMode = defaultAutoReceiptMode;

    private final Set<ReceiptReceivedListener> receiptReceivedListeners = new CopyOnWriteArraySet<ReceiptReceivedListener>();

    private DeliveryReceiptManager(XMPPConnection connection) {
        super(connection);
        ServiceDiscoveryManager sdm = ServiceDiscoveryManager.getInstanceFor(connection);
        sdm.addFeature(DeliveryReceipt.NAMESPACE);

        // Add the packet listener to handling incoming delivery receipts
        connection.addAsyncStanzaListener(new StanzaListener() {
            @Override
            public void processStanza(Stanza packet) throws NotConnectedException {
                DeliveryReceipt dr = DeliveryReceipt.from((Message) packet);
                // notify listeners of incoming receipt
                for (ReceiptReceivedListener l : receiptReceivedListeners) {
                    l.onReceiptReceived(packet.getFrom(), packet.getTo(), dr.getId(), packet);
                }
            }
        }, MESSAGES_WITH_DELIVERY_RECEIPT);

        // Add the packet listener to handle incoming delivery receipt requests
        connection.addAsyncStanzaListener(new StanzaListener() {
            @Override
            public void processStanza(Stanza packet) throws NotConnectedException, InterruptedException {
                final Jid from = packet.getFrom();
                final XMPPConnection connection = connection();
                switch (autoReceiptMode) {
                case disabled:
                    return;
                case ifIsSubscribed:
                    if (!Roster.getInstanceFor(connection).isSubscribedToMyPresence(from)) {
                        return;
                    }
                    break;
                case always:
                    break;
                }

                final Message messageWithReceiptRequest = (Message) packet;
                Message ack = receiptMessageFor(messageWithReceiptRequest);
                if (ack == null) {
                    LOGGER.warning("Received message stanza with receipt request from '" + from
                                    + "' without a stanza ID set. Message: " + messageWithReceiptRequest);
                    return;
                }
                connection.sendStanza(ack);
            }
        }, NON_ERROR_GROUPCHAT_MESSAGES_WITH_DELIVERY_RECEIPT_REQUEST);
    }

    /**
     * Obtain the DeliveryReceiptManager responsible for a connection.
     *
     * @param connection the connection object.
     *
     * @return the DeliveryReceiptManager instance for the given connection
     */
     public static synchronized DeliveryReceiptManager getInstanceFor(XMPPConnection connection) {
        DeliveryReceiptManager receiptManager = instances.get(connection);

        if (receiptManager == null) {
            receiptManager = new DeliveryReceiptManager(connection);
            instances.put(connection, receiptManager);
        }

        return receiptManager;
    }

    /**
     * Returns true if Delivery Receipts are supported by a given JID.
     *
     * @param jid TODO javadoc me please
     * @return true if supported
     * @throws SmackException if there was no response from the server.
     * @throws XMPPException if an XMPP protocol error was received.
     * @throws InterruptedException if the calling thread was interrupted.
     */
    public boolean isSupported(Jid jid) throws SmackException, XMPPException, InterruptedException {
        return ServiceDiscoveryManager.getInstanceFor(connection()).supportsFeature(jid,
                        DeliveryReceipt.NAMESPACE);
    }

    /**
     * Configure whether the {@link DeliveryReceiptManager} should automatically
     * reply to incoming {@link DeliveryReceipt}s.
     *
     * @param autoReceiptMode the new auto receipt mode.
     * @see AutoReceiptMode
     */
    public void setAutoReceiptMode(AutoReceiptMode autoReceiptMode) {
        this.autoReceiptMode = autoReceiptMode;
    }

    /**
     * Get the currently active auto receipt mode.
     *
     * @return the currently active auto receipt mode.
     */
    public AutoReceiptMode getAutoReceiptMode() {
        return autoReceiptMode;
    }

    /**
     * Get informed about incoming delivery receipts with a {@link ReceiptReceivedListener}.
     *
     * @param listener the listener to be informed about new receipts
     */
    public void addReceiptReceivedListener(ReceiptReceivedListener listener) {
        receiptReceivedListeners.add(listener);
    }

    /**
     * Stop getting informed about incoming delivery receipts.
     *
     * @param listener the listener to be removed
     */
    public void removeReceiptReceivedListener(ReceiptReceivedListener listener) {
        receiptReceivedListeners.remove(listener);
    }

    /**
     * A filter for stanzas to request delivery receipts for. Notably those are message stanzas of type normal, chat or
     * headline, which <b>do not</b>contain a delivery receipt, i.e. are ack messages, and have a body extension.
     *
     * @see <a href="http://xmpp.org/extensions/xep-0184.html#when-ack">XEP-184 § 5.4 Ack Messages</a>
     */
    private static final StanzaFilter MESSAGES_TO_REQUEST_RECEIPTS_FOR = new AndFilter(
                    // @formatter:off
                    MessageTypeFilter.NORMAL_OR_CHAT_OR_HEADLINE,
                    new NotFilter(new StanzaExtensionFilter(DeliveryReceipt.ELEMENT, DeliveryReceipt.NAMESPACE)),
                    MessageWithBodiesFilter.INSTANCE
                    );
                   // @formatter:on

    /**
     * Enables automatic requests of delivery receipts for outgoing messages of
     * {@link org.jivesoftware.smack.packet.Message.Type#normal}, {@link org.jivesoftware.smack.packet.Message.Type#chat} or {@link org.jivesoftware.smack.packet.Message.Type#headline}, and
     * with a {@link org.jivesoftware.smack.packet.Message.Body} extension.
     *
     * @since 4.1
     * @see #dontAutoAddDeliveryReceiptRequests()
     */
    public void autoAddDeliveryReceiptRequests() {
        connection().addMessageInterceptor(DeliveryReceiptRequest::addTo, m -> {
            return MESSAGES_TO_REQUEST_RECEIPTS_FOR.accept(m);
        });
    }

    /**
     * Disables automatically requests of delivery receipts for outgoing messages.
     *
     * @since 4.1
     * @see #autoAddDeliveryReceiptRequests()
     */
    public void dontAutoAddDeliveryReceiptRequests() {
        connection().removeMessageInterceptor(DeliveryReceiptRequest::addTo);
    }

    /**
     * Test if a message requires a delivery receipt.
     *
     * @param message Stanza object to check for a DeliveryReceiptRequest
     *
     * @return true if a delivery receipt was requested
     */
    public static boolean hasDeliveryReceiptRequest(Message message) {
        return DeliveryReceiptRequest.from(message) != null;
    }

    /**
     * Add a delivery receipt request to an outgoing packet.
     *
     * Only message packets may contain receipt requests as of XEP-0184,
     * therefore only allow Message as the parameter type.
     *
     * @param m Message object to add a request to
     * @return the Message ID which will be used as receipt ID
     * @deprecated use {@link DeliveryReceiptRequest#addTo(Message)}
     */
    @Deprecated
    public static String addDeliveryReceiptRequest(Message m) {
        return DeliveryReceiptRequest.addTo(m);
    }

    /**
     * Create and return a new message including a delivery receipt extension for the given message.
     * <p>
     * If {@code messageWithReceiptRequest} does not have a Stanza ID set, then {@code null} will be returned.
     * </p>
     *
     * @param messageWithReceiptRequest the given message with a receipt request extension.
     * @return a new message with a receipt or <code>null</code>.
     * @since 4.1
     */
    public static Message receiptMessageFor(Message messageWithReceiptRequest) {
        String stanzaId = messageWithReceiptRequest.getStanzaId();
        if (StringUtils.isNullOrEmpty(stanzaId)) {
            return null;
        }
        Message message = StanzaBuilder.buildMessage()
                .ofType(messageWithReceiptRequest.getType())
                .to(messageWithReceiptRequest.getFrom())
                .addExtension(new DeliveryReceipt(stanzaId))
                .build();
        return message;
    }
}
